The present invention relates to golf balls and, in particular, to self-healing polymeric compositions useful in golf ball covers, cores, and intermediate to improve the durability of the golf ball during the impact.
The majority of golf balls commercially available today can be grouped into two general classes: solid and wound. Solid golf balls include one-piece, two-piece, and multi-layer golf balls. One-piece golf balls are inexpensive and easy to construct, but have limited playing characteristics and their use is usually confined to the driving range. Two-piece balls are generally constructed with a polybutadiene solid core and a cover and are typically the most popular with recreational golfers because they are very durable and provide good distance. These balls are also relatively inexpensive and easy to manufacture, but are regarded by top players as having limited playing characteristics. Multi-layer golf balls are comprised of a solid core and a cover, either of which may be formed of one or more layers. These balls are regarded as having an extended range of playing characteristics, but are more expensive and difficult to manufacture than are one-and two-piece golf balls.
Wound golf balls, which typically include a fluid-filled center surrounded by tensioned elastomeric material and a cover, are preferred by many players due to their spin and xe2x80x9cfeelxe2x80x9d characteristics but are more difficult and expensive to manufacture than are most solid golf balls. Manufacturers are constantly striving, therefore, to produce a solid ball that retains the beneficial characteristics of a solid ball while concurrently exhibiting the beneficial characteristics of a wound ball.
Golf ball playing characteristics, such as compression, velocity, xe2x80x9cfeel,xe2x80x9d and, therefore, spin, can be adjusted and optimized by manufacturers to suit players having a wide variety of playing abilities. For example, manufacturers can alter any or all of these properties by changing the materials (i.e., polymer compositions) and/or the physical construction of each or all of the various golf ball components (i.e., centers, cores, intermediate layers, and covers). Finding the right combination of core and layer materials and the ideal ball construction to produce a golf ball suited for a predetermined set of performance criteria is a challenging task.
The present invention is related to golf ball materials comprising at least one polymer and at least one microencapsulated healing agent to improve impact durability. Polymers are macromolecules built up by the linking together of large number of smaller molecules called monomers. Upon repetitive impact, the golf balls formed of many types of polymers tend to develop micro-cracks. One aspect of this invention is a way to make a polymeric golf ball component that contains very small spheres or capsules filled (microencapsulated) with a healing liquid containing monomer molecules. Without wishing to be bound by any particular theory, it is believed that as these micro-cracks get bigger, they come into contact with a microcapsule, bursting the microcapsule(s) and releasing the monomer liquid into the crack. Ring-opening metathesis polymerization occurs when in contact with a catalyst present in the polymer matrix. The catalyst in the polymer is able to react with the liquid monomer. The chemical reaction between the liquid monomer and the catalyst creates polymer molecules that xe2x80x9crepairxe2x80x9d the crack. The repaired plastic is believed to regain much of the strength of undamaged polymeric material. There is, therefore, a need for development of suitable healing agents that can be utilized to impart improved durability to golf ball cores, covers, and intermediate layers.
The present invention is directed to a 1. A golf ball comprising a core and a cover disposed concentrically about the core, wherein at least one of the core of the cover is formed of a composition comprising a microencapsulated healing agent. The healing agent is present in an amount between about 0.1% and about 20.0% of the polymer by weight.
In one embodiment, the core comprises a center and an outer core layer. The center may be a solid center, or it may be a hollow, gel, or fluid center. The cover may be formed as an inner cover layer and an outer cover layer.
The polymer includes ionomers and acid precursors, polyolefins, polycarbonates, polyarylates, polyimides, polyphenylene oxide, polyether, silicones, polysiloxanes, polyisporene, block copoly(ether or ester-amide), block copoly(ether or ester-ester), polysulfones, reaction injection moldable thermoplastic and thermoset polymers, block copolymer of styrene-butadiene and its hydrogenated derivatives, dynamically vulcanized ethylene-propylene rubber, polyvinylidenefluoride, acrylocnitrile-butadiene styrene copolymer, polyurethanes, polyureas, epoxy resins, polystyrenes, acrylics, polyethylenes, polycarbonates, polyamides, polybutadienes, polyesters, or a mixture thereof. The polymer has a flexural modulus of from about 2,000 psi to 200,000 psi. At least one of the core or cover is foamed, comprises a density-modifying filler, or both.
The microencapsulated healing agent includes a polycyclic organic moiety or its functionalized derivatives and is preferably contained in a capsule less than about 500 microns in diameter. The microencapsulated healing agent is contained in a capsule less than about 100 microns or smaller. Preferably, the capsule is a shell comprising urea-formaldehyde.
The composition further comprises a catalyst. Preferably, the catalyst comprises a Grubb""s catalyst, a ruthenium-based catalyst, an iron-based catalyst, an osmium catalyst, a living polymerization catalyst, a transition metal catalyst, or a mixture thereof.
The present invention is also directed to a golf ball comprising a core, a cover disposed concentrically about the core, and an optional intermediate layer, wherein at least one of the cover, the core, or the optional intermediate layer is formed of a self-healing polymer comprising a base polymer, a microencapsulated healing agent, and a catalyst. The intermediate layer may include a tensioned elastomeric material or an outer core layer or an inner cover layer.
The catalyst includes a Grubb""s catalyst, a ruthenium-based catalyst, an iron-based catalyst, an osmium catalyst, a living-polymerization catalyst, a transition metal catalyst, or a mixture thereof. The intermediate layer can be an inner or outer cover layer having a thickness of between about 0.03 inches and about 0.125 inches.
The present invention is further directed to a composition for golf equipment, wherein the composition comprises a self-healing polymer comprising a microencapsulated healing agent. The golf equipment may include a putter insert, golf shoes, and golf shoe components.